// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file contains methods to iterate over processes on the system.

#ifndef BASE_PROCESS_PROCESS_ITERATOR_H_
#define BASE_PROCESS_PROCESS_ITERATOR_H_

#include <stddef.h>

#include <list>
#include <string>
#include <vector>

#include "base/base_export.h"
#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/process/process.h"
#include "build/build_config.h"

#if defined(OS_WIN)
#include <tlhelp32.h>
#include <windows.h>
#elif defined(OS_MACOSX) || defined(OS_OPENBSD)
#include <sys/sysctl.h>
#elif defined(OS_FREEBSD)
#include <sys/user.h>
#elif defined(OS_POSIX)
#include <dirent.h>
#endif

namespace base {

#if defined(OS_WIN)
struct ProcessEntry : public PROCESSENTRY32 {
    ProcessId pid() const { return th32ProcessID; }
    ProcessId parent_pid() const { return th32ParentProcessID; }
    const wchar_t* exe_file() const { return szExeFile; }
};
#elif defined(OS_POSIX)
struct BASE_EXPORT ProcessEntry {
    ProcessEntry();
    ProcessEntry(const ProcessEntry& other);
    ~ProcessEntry();

    ProcessId pid() const { return pid_; }
    ProcessId parent_pid() const { return ppid_; }
    ProcessId gid() const { return gid_; }
    const char* exe_file() const { return exe_file_.c_str(); }
    const std::vector<std::string>& cmd_line_args() const
    {
        return cmd_line_args_;
    }

    ProcessId pid_;
    ProcessId ppid_;
    ProcessId gid_;
    std::string exe_file_;
    std::vector<std::string> cmd_line_args_;
};
#endif // defined(OS_POSIX)

// Used to filter processes by process ID.
class ProcessFilter {
public:
    // Returns true to indicate set-inclusion and false otherwise.  This method
    // should not have side-effects and should be idempotent.
    virtual bool Includes(const ProcessEntry& entry) const = 0;

protected:
    virtual ~ProcessFilter() { }
};

// This class provides a way to iterate through a list of processes on the
// current machine with a specified filter.
// To use, create an instance and then call NextProcessEntry() until it returns
// false.
class BASE_EXPORT ProcessIterator {
public:
    typedef std::list<ProcessEntry> ProcessEntries;

    explicit ProcessIterator(const ProcessFilter* filter);
    virtual ~ProcessIterator();

    // If there's another process that matches the given executable name,
    // returns a const pointer to the corresponding PROCESSENTRY32.
    // If there are no more matching processes, returns NULL.
    // The returned pointer will remain valid until NextProcessEntry()
    // is called again or this NamedProcessIterator goes out of scope.
    const ProcessEntry* NextProcessEntry();

    // Takes a snapshot of all the ProcessEntry found.
    ProcessEntries Snapshot();

protected:
    virtual bool IncludeEntry();
    const ProcessEntry& entry() { return entry_; }

private:
    // Determines whether there's another process (regardless of executable)
    // left in the list of all processes.  Returns true and sets entry_ to
    // that process's info if there is one, false otherwise.
    bool CheckForNextProcess();

    // Initializes a PROCESSENTRY32 data structure so that it's ready for
    // use with Process32First/Process32Next.
    void InitProcessEntry(ProcessEntry* entry);

#if defined(OS_WIN)
    HANDLE snapshot_;
    bool started_iteration_;
#elif defined(OS_MACOSX) || defined(OS_BSD)
    std::vector<kinfo_proc> kinfo_procs_;
    size_t index_of_kinfo_proc_;
#elif defined(OS_POSIX)
    DIR* procfs_dir_;
#endif
    ProcessEntry entry_;
    const ProcessFilter* filter_;

    DISALLOW_COPY_AND_ASSIGN(ProcessIterator);
};

// This class provides a way to iterate through the list of processes
// on the current machine that were started from the given executable
// name.  To use, create an instance and then call NextProcessEntry()
// until it returns false.
class BASE_EXPORT NamedProcessIterator : public ProcessIterator {
public:
    NamedProcessIterator(const FilePath::StringType& executable_name,
        const ProcessFilter* filter);
    ~NamedProcessIterator() override;

protected:
    bool IncludeEntry() override;

private:
    FilePath::StringType executable_name_;

    DISALLOW_COPY_AND_ASSIGN(NamedProcessIterator);
};

// Returns the number of processes on the machine that are running from the
// given executable name.  If filter is non-null, then only processes selected
// by the filter will be counted.
BASE_EXPORT int GetProcessCount(const FilePath::StringType& executable_name,
    const ProcessFilter* filter);

} // namespace base

#endif // BASE_PROCESS_PROCESS_ITERATOR_H_
